In copper electrowinning, a pure copper starter cathode sheet is immersed in a copper bearing liquid electrolyte together with a lead or lead alloy anode. Electrical current is passed between the anode and the cathode which deposits copper from the electrolyte onto the copper cathode starter sheet. As the copper bearing electrolyte is depleted, it is replenished. Ideally, there will be no transfer of the lead or lead alloy from the anode to the cathode by the passage of the current. As a practical matter, however, there is a transfer of small amounts of lead and/or lead alloy to the cathode. So long as the amount of lead or lead alloy passed is sufficiently low, the purity requirements of the deposited copper are met and there is no requirement that the copper cathode be put through an additional electrorefining process. The additional expense of electrorefining is apparent.
It has been ascertained that the lead or lead alloy anodes which perform most efficiently are anodes which present a smooth, dense, close-grained surface and which make good contact about the hanger bar to which they are attached, both mechanically and electrically.
In the past the lead or lead alloy anodes have been made from rolled plate which has been cut to size and to which the hanger bar has been attached by means for rivets. Additionally the anodes have been cast from lead or lead alloy, both for later mechanical connection to the hanger bar or cast about the hanger bar. Clearly cost factors dictate that if the desired characteristics can be obtained by casting then such should be the method employed. It is to this latter method to which the subject invention is directed.